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TZSET(3P)                  POSIX Programmer's Manual                 TZSET(3P)
PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       daylight, timezone, tzname, tzset -- set timezone  conversion  informa-
       tion
SYNOPSIS
       #include <time.h>
       extern int daylight;
       extern long timezone;
       extern char *tzname[2];
       void tzset(void);
DESCRIPTION
       The tzset() function shall use the value of the environment variable TZ
       to set  time  conversion  information  used  by  ctime(),  localtime(),
       mktime(), and strftime().  If TZ is absent from the environment, imple-
       mentation-defined default timezone information shall be used.
       The tzset() function shall set the external variable tzname as follows:
           tzname[0] = "std";
           tzname[1] = "dst";
       where std and dst are as described in the Base  Definitions  volume  of
       POSIX.1-2008, Chapter 8, Environment Variables.
       The tzset() function also shall set the external variable daylight to 0
       if Daylight Savings Time conversions should never be  applied  for  the
       timezone  in  use;  otherwise, non-zero. The external variable timezone
       shall be set to the difference, in seconds, between Coordinated Univer-
       sal Time (UTC) and local standard time.
RETURN VALUE
       The tzset() function shall not return a value.
ERRORS
       No errors are defined.
       The following sections are informative.
EXAMPLES
       Example  TZ  variables  and their timezone differences are given in the
       table below:
                              +-----------+------------+
                              |    TZ     |  timezone  |
                              +-----------+------------+
                              |EST5EDT    | 5*60*60    |
                              |GMT0       | 0*60*60    |
                              |JST-9      | -9*60*60   |
                              |MET-1MEST  | -1*60*60   |
                              |MST7MDT    | 7*60*60    |
                              |PST8PDT    | 8*60*60    |
                              +-----------+------------+
APPLICATION USAGE
       None.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       ctime(), localtime(), mktime(), strftime()
       The Base Definitions volume of  POSIX.1-2008,  Chapter  8,  Environment
       Variables, <time.h>
COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.unix.org/online.html .
       Any typographical or formatting errors that appear  in  this  page  are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors,  see  https://www.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                            TZSET(3P)